On the annual cycle of coastal and open ocean satellite chlorophyll off Chile (18°–40°S)

Abstract

High resolution SeaWiFS (Sea‐viewing Wide Field‐of‐view Sensor) chlorophyll and satellite wind data (1997–2004) are used to analyze the coastal and oceanic behavior of sea surface chlorophyll (CHL) concentration in the eastern boundary current system off Chile (18°–40°S). Two contrasting regimes are evident; a coastal regime, where CHL maximum occurs during summer, coinciding with the maximum upwelling‐favorable wind stress and an offshore regime, where the CHL maximum is in winter and is not related to the maximum wind (stress, curl). Moreover, our analysis reveals that the annual coastal CHL cycle is strong along the entire latitudinal extension, contrary to previous observations that showed a weak seasonal cycle off northern Chile. Averaging ocean‐color data across spatial domains where different forcings and processes operate will lead to unreliable retrieval of pigment biomass. Proper characterization of biological processes in upwelling and coastal regions requires deriving statistics over the relevant spatial scales.